The present invention relates to home laundry appliances and particularly, washing machines of the type having a receptacle filled with fluid into which the articles to be washed are immersed and agitated in the fluid by a motor driven mechanism. Washing machines of this type usually have solenoid operated filling valves for controlling the flow of water into the receptacle. Typically, a fluid level sensing switch actuates the solenoid fill valves to admit water when the machine is initially turned on or at the end of various washing and rinsing cycles when the water has been drained from the receptacle. The fluid level switch deactivates the filling valve when the level in the receptacle reaches the desired level for washing. It is known to utilize separate solenoid operated fill valves for the hot and cold water inlets to the machine to enable selective hot or cold filling or a mixing of the hot and cold water supply to produce washing liquid of an intermediate temperature.
It is known to activate the solenoid operated filling valves by a motor driven timer which in turn is energized by a centrifugal switch attached to the main agitation and spin motor. This arrangement prevents water from entering the washing receptacle or tub until the cycle control timer is operative. It is also known to utilize a two-stage flow control arrangement for initially filling the tub at a high rate of flow and upon the water in the tub reaching the desired level, changing to a lower flow rate for replenishing the water discharged from the tub during the various washing and rinsing cycles. In the typical washing machine the timer motor drives a set of cams which actuate electrical contacts for making and breaking circuits to energize the fill valve solenoids in the proper time sequence and for the desired time intervals.
In order to improve the laundering efficiency of washing machines, it has been found desirable to interrupt the flow of water to the tub during periods of agitation to permit the articles to be agitated in water and detergent wherein the articles are agitated in varying levels of water, detergent and suds mixture in differing proportions for specified intervals of time. Thus, it has been found desirable to not only selectively vary the temperature of the water entering the tub for various fabric cycles and to provide initial rapid fill with a subsequent lower rate fill during the washing cycle, but also to provide means for intermittently interrupting the flow of water to the tub during agitation. This combination of requirements has necessitated the use of a plurality of filling and flow control solenoid valves to provide the desired control functions for the tub filling.
One known technique for providing the aforesaid control of the tub water fill during the washing cycles is shown in FIG. 1 as employing the usual separate hot and cold solenoid operated filling valves, the output of which are mixed and applied to the inlet of respectively separate solenoid operated high and low flow rate control valves. This arrangement permits the separate timed energization of the hot and cold filling valves for providing the appropriate water temperature and separate timed activation of the high or low flow control valve to admit the water of the desired temperature at the desired flow rate. In the prior art arrangement of FIG. 1 the separate high and low flow solenoid operated flow control valves are energized by switches activated by separate control cams on the motor driven washing machine timer. The disadvantage of the prior art system shown in FIG. 1 is that it requires four individual solenoid operated valves to accomplish the desired water fill control functions. The water fill control system of such a prior art system is costly to manufacture and wasteful energy, because at least either the hot or cold fill valve coil and either the high or low flow control valve solenoids must be actuated during washing operation and thus a continuous power drain for two solenoid valves is encountered.
Another known scheme for providing control of the water filling functions of a washing machine of the above described type is shown in FIG. 3 wherein only three solenoid operated water valves are employed. The prior art system of FIG. 3 employs the usual individual hot and cold temperature selection filling valves respectively having their inlets connected to the hot and cold water line with the outlets thereof mixed applied to the inlet of a flow control valve. The flow control valve of the prior art system of FIG. 3 is a solenoid operated valve which provides a high rate of flow upon activation of the solenoid; and, when the solenoid is deenergized the valve provides a continuous flow at a substantially lower rate. The prior art system of FIG. 3 has no provision for the electrical power interruption and restart of the water flow to the machine during the normal washing, rinsing and agitation cycles. The prior art system of FIG. 3 after the initial fast fill of the tub and during normal washing and rinsing operations requires that at least one of the temperature selection filling valves be continuously activated, and thus requires continuous energization of one less valve than the prior art scheme of FIG. 1. However, the prior art system of FIG. 3 does not permit machine cycle restart after electrical power interruption of water flow to the machine tub. The prior art system of FIG. 3 relies on the fluid level switch to terminate all water flow when the tub is full. It will be recognized by those skilled in the art that in the known system of FIG. 3, if line power is interrupted with all the timer controlled switches in the open position except "MTR ON" and with the fluid level in the "F" position, upon resumption of line power, the main motor will not restart unless the timer is manually repositioned to close the "motor by-pass" switch. Further, it will be apparent that in the known system of FIG. 3, if line power is interrupted with fluid level switch in the "E" position (tub drained) and timer switches are open, the timer must be manually restarted to close the "timer on-off" switch in order to reenergize the filling valves to fill the tub.
It has thus been desired to provide a water fill control system for a domestic washing machine wherein the filling of the tub with water at the preselected temperature may be staged or performed at timed intervals with selected dwell periods therebetween while the machine is agitating during the wash and rinse cycles. It has thus been desired to find a way of utilizing the cycle timer of the machine to control the water filling rate and schedule rather than leaving the control of the water fill to the liquid level sensor in the machine tub.